Re: [HACKERS] NOT NULL violation error handling in file_fdw
(2012/03/12 19:21), Etsuro Fujita wrote: According to the following documentation on IterateForeignScan() in 50.2. Foreign Data Wrapper Callback Routines, I have created a patch to support the error handling in file_fdw. Please find attached a patch. Note that PostgreSQL's executor doesn't care whether the rows returned violate the NOT NULL constraints which were defined on the foreign table columns - but the planner does care, and may optimize queries incorrectly if NULL values are present in a column declared not to contain them. If a NULL value is encountered when the user has declared that none should be present, it may be appropriate to raise an error (just as you would need to do in the case of a data type mismatch). Interesting. This patch could be applied cleanly, and it catches first record which violates NOT NULL constraint. I have some comments for the patch. I worry performance degradation caused by checking NOT NULL constraints for every row, though such overhead might be hidden by disk I/O. Do you have any result of performance testing? Users might want to disable NOT NULL checking for already-validated files. In addition to performance issue, IMHO exporting ExecBuildSlotValueDescription needs more consideration. Have you examined calling ExecConstraints instead of copying NOT NULL check codes? It requires fully-built ResultRelInfo, and it also checks CHECK constraints which have not been supported on foreign tables, but it seems the standard way to apply constraints on a tuple. If you don't want to check CHECK constraints, another possible idea is to add new external function ExecNotNull (or something) and move NOT NULL checking codes from ExecConstraints, and call it from fileIterateForeignScan and ExecConstraints. Anyway, please add this patch to Commit Fest App for tracking. https://commitfest.postgresql.org/action/commitfest_view?id=14 -- Shigeru Hanada -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] NOT NULL violation error handling in file_fdw
(2012/03/13 15:53), Shigeru HANADA wrote: (2012/03/12 19:21), Etsuro Fujita wrote: According to the following documentation on IterateForeignScan() in 50.2. Foreign Data Wrapper Callback Routines, I have created a patch to support the error handling in file_fdw. Please find attached a patch. Interesting. This patch could be applied cleanly, and it catches first record which violates NOT NULL constraint. I have some comments for the patch. Thank you for the review. I worry performance degradation caused by checking NOT NULL constraints for every row, though such overhead might be hidden by disk I/O. Do you have any result of performance testing? Users might want to disable NOT NULL checking for already-validated files. I don't have any numbers for now. OK I'll check it. In addition to performance issue, IMHO exporting ExecBuildSlotValueDescription needs more consideration. Have you examined calling ExecConstraints instead of copying NOT NULL check codes? It requires fully-built ResultRelInfo, and it also checks CHECK constraints which have not been supported on foreign tables, but it seems the standard way to apply constraints on a tuple. Yes, I thought the use of ExecConstraints(). But I feel that it is an overkill. If you don't want to check CHECK constraints, another possible idea is to add new external function ExecNotNull (or something) and move NOT NULL checking codes from ExecConstraints, and call it from fileIterateForeignScan and ExecConstraints. I think that it is a good idea. I'll do it at the next version of the patch. Anyway, please add this patch to Commit Fest App for tracking. https://commitfest.postgresql.org/action/commitfest_view?id=14 Done. Best regards, Etsuro Fujita -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
[HACKERS] NOT NULL violation error handling in file_fdw
According to the following documentation on IterateForeignScan() in
50.2. Foreign Data Wrapper Callback Routines, I have created a patch to
support the error handling in file_fdw. Please find attached a patch.
Note that PostgreSQL's executor doesn't care whether the rows
returned violate the NOT NULL constraints which were defined
on the foreign table columns - but the planner does care, and
may optimize queries incorrectly if NULL values are present
in a column declared not to contain them. If a NULL value is
encountered when the user has declared that none should be
present, it may be appropriate to raise an error (just as you
would need to do in the case of a data type mismatch).
Best regards,
Etsuro Fujita
*** a/contrib/file_fdw/file_fdw.c
--- b/contrib/file_fdw/file_fdw.c
***
*** 502,507 fileIterateForeignScan(ForeignScanState *node)
--- 502,510
{
FileFdwExecutionState *festate = (FileFdwExecutionState *)
node-fdw_state;
TupleTableSlot *slot = node-ss.ss_ScanTupleSlot;
+ Relationrel = node-ss.ss_currentRelation;
+ TupleConstr *constr = rel-rd_att-constr;
+ boolhas_not_null = (constr != NULL) ? constr-has_not_null
: false;
boolfound;
ErrorContextCallback errcontext;
***
*** 528,534 fileIterateForeignScan(ForeignScanState *node)
--- 531,556
slot-tts_values,
slot-tts_isnull,
NULL);
if (found)
+ {
ExecStoreVirtualTuple(slot);
+ if (has_not_null)
+ {
+ int natts = rel-rd_att-natts;
+ int attrChk;
+
+ for (attrChk = 1; attrChk = natts; attrChk++)
+ {
+ if (rel-rd_att-attrs[attrChk - 1]-attnotnull
+ slot_attisnull(slot, attrChk))
+ ereport(ERROR,
+
(errcode(ERRCODE_NOT_NULL_VIOLATION),
+errmsg(null value in
column \%s\ violates not-null constraint,
+
NameStr(rel-rd_att-attrs[attrChk - 1]-attname)),
+errdetail(Failing row
contains %s.,
+
ExecBuildSlotValueDescription(slot, 64;
+ }
+ }
+ }
/* Remove error callback. */
error_context_stack = errcontext.previous;
*** a/src/backend/executor/execMain.c
--- b/src/backend/executor/execMain.c
***
*** 86,93 static void ExecutePlan(EState *estate, PlanState *planstate,
DestReceiver *dest);
static bool ExecCheckRTEPerms(RangeTblEntry *rte);
static void ExecCheckXactReadOnly(PlannedStmt *plannedstmt);
- static char *ExecBuildSlotValueDescription(TupleTableSlot *slot,
-
int maxfieldlen);
static void EvalPlanQualStart(EPQState *epqstate, EState *parentestate,
Plan *planTree);
static void OpenIntoRel(QueryDesc *queryDesc);
--- 86,91
***
*** 1604,1610 ExecConstraints(ResultRelInfo *resultRelInfo,
* here since heap field values could be very long, whereas index entries
* typically aren't so wide.
*/
! static char *
ExecBuildSlotValueDescription(TupleTableSlot *slot, int maxfieldlen)
{
StringInfoData buf;
--- 1602,1608
* here since heap field values could be very long, whereas index entries
* typically aren't so wide.
*/
! char *
ExecBuildSlotValueDescription(TupleTableSlot *slot, int maxfieldlen)
{
StringInfoData buf;
*** a/src/include/executor/executor.h
--- b/src/include/executor/executor.h
***
*** 184,189 extern ResultRelInfo *ExecGetTriggerResultRel(EState *estate,
Oid relid);
--- 184,191
extern bool ExecContextForcesOids(PlanState *planstate, bool *hasoids);
extern void ExecConstraints(ResultRelInfo *resultRelInfo,
TupleTableSlot *slot, EState *estate);
+ extern char *ExecBuildSlotValueDescription(TupleTableSlot *slot,
+
int maxfieldlen);
extern ExecRowMark *ExecFindRowMark(EState *estate, Index rti);
extern ExecAuxRowMark *ExecBuildAuxRowMark(ExecRowMark *erm, List
*targetlist);
extern TupleTableSlot *EvalPlanQual(EState *estate, EPQState *epqstate,
--
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